Technical Field
The present disclosure relates to a radio frequency switching system.
Background Art
Radio frequency switching systems, commonly known as RF switches, are widely used in the telecommunications sector and may be used for a whole range of different purposes.
An RF switch generally performs the two main functions of receiving and transmitting and is piloted as a function of input and external conditions.
One of the main problems to be faced with reference to high power RF switches is that of energy consumption, which must necessarily be limited in order to obtain an optimized RF switch.
FIG. 1 and FIG. 2 show a possible embodiment of an RF switch of known type made using PIN diodes, in a receiving configuration and in a transmission configuration, respectively. Such embodiment shown in the illustrations represents a possible example and is not the only possible embodiment.
Exploiting the potential difference VL, a current I, approximately equal to about 100 mA, runs through a resistance R and reaches the section of the PIN diodes D1, D2, D3 and D4.
The high-frequency resistance R is inversely proportionate to the polarization direct current that crosses the diode. A high current crossing the diode is necessary to obtain a low resistance to such high frequency.
In the receiving configuration of the RF switch, shown in FIG. 1, the PIN diode D1 is forward biased (crossed by a current IFWD) and, therefore, in low resistance for the RF signal and the circuit closes to ground in the left portion, making the RF Rx port active.
Thanks to the high potential difference VH, in such configuration all the other PIN diodes D2, D3 and D4 are reverse biased and act as high resistance for the RF signal, thus preventing the flow of current through them.
In the transmission configuration of the RF switch, shown in FIG. 2, the PIN diodes D2, D3 and D4 are forward biased, while the diode D1 is reverse biased. In such case, therefore, the current flows to the right, making the port RF Tx active.
In the receiving configuration, considering a potential difference VL=5V and a potential difference VH=28V, with I=100 mA, the consumption of energy is equal to about Pdiss=VL×I=0.5 W and this is a consumption value that can be considered reasonable for this state of operation.
In particular, this is due to the quantity of power dissipated by the forward-biased resistance, used to regulate the flow of current generated by the potential difference VL.
On the other hand, the consumption of energy in the transmission configuration, considering a potential difference VL=5V and a potential difference VH=28V, with I=100 mA, it is equal to about Pdiss=VL×I+VH×I=0.5 W+2.8 W=3.3 W and is considerably high.
In particular, in this configuration as well, such consumption is due to the portion of power dissipated by the forward-biased resistance which is used to regulate the flow of current.
In such case, nevertheless, the potential difference VH is much higher because it is used to operate the PIN diodes in reverse bias to act as high resistance for high-frequency RF signals.